KR20080063233A - Fullerene derivatives - Google Patents

Abstract

A fullerene derivative of a pentapod structure is provided to obtain a fullerene derivative capable of acting as monomolecular rectifier by asymmetrical structure. A fullerene derivative of a pentapod structure is represented by the formula 1, wherein RX is a functional group containing sulfur. Preferably R of the RX is a linear or branched saturated or unsaturated alkyl or aryl group; and X of the RX is a functional moiety capable of adsorbed to the surface of a substrate by a structure of -SH or -S-S-.

Description

Fullerene derivatives {Fullerene derivatives}

The present invention relates to a fullerene derivative, and more particularly, a method of thiolating to introduce a pentaphore-structured amphiphilic fullerene derivative having a variety of functional groups containing sulfur, and parents having molecular arrangements on a conductive substrate using the same. It relates to a rectifier using a medium fullerene derivative.

Since fullerene molecules have strong hydrophobic properties, they are easily aggregated with each other, and it is very difficult to uniformly arrange them on the substrate. However, in the literature, there have been many reports of attempts to form a self-assembled monolayer (SAM) of fullerene in order to arrange well and densely on a substrate.

For example, it has been reported that the Au(111) substrate was treated with (4-mercaptophenyl) anthrylacetylene (MPAA)) to achieve stable self-assembly. As a result of this, in order to achieve an improved molecular arrangement, in the present invention, a more stable nano-sized monomolecular layer (mono layer).

Looking at the research related to the organic rectifier, ^{it consists of a D-δ-A system in which 1} electron donor part (D) is connected to the electron acceptor part (A) through an insulated δ bridge. ² Single-molecule rectification characteristics were detected through a single membrane of Lanmuir-Blodgett (LB) of hexadecylquinolinium tricyanoquinodimethanide ³ and confirmed later ^4,5 . The fullerene derivative LB single-film rectifier was found when sandwiched between gold electrodes ⁶ . This first fullerene derivative compound, dimethylaminophenylazafullerene, has been reported to have a very pronounced rectification ratio (up to 20,000). However, it is believed that most of the forward current is due to the formation of stalagmite in gold. In other studies, fullerene-bis-[4-diphenylamino-4''-( N -ethyl- N -2'''-ethyl)amino-1,4-diphenyl-1,3-butadiene] ⁷ Langmuir- of malonate Schaefer(LS) reported that a single thin film exhibited rectification when sandwiched between two gold electrodes.

Fullerene molecules are strongly hydrophobic and easily aggregated. However, many attempts have been reported in the literature to form a fullerene SAM in order to align well and densely on a substrate ⁸ . Stable self-assembly of (4-mercaptophenyl)anthrylacetylene (MPAA) on gold (111) substrate has been reported ⁹ . This molecule has a very good 2D alignment through strong pp intermolecular clusters and gold-thiol attraction. Thus, the excellent physical and chemical properties of fullerene are combined with the advantages that can be obtained by controlling the nano-sized alignment of the MPAA-based SAM.

Nakamura and his team added an organo-copper reagent to bind the penta-addition material to the fullerene. ¹⁰ This reaction is quantitative, can be tested on a multi-gram basis, and is very common for a variety of aryl and alkenyl groups as well as methyl groups. ¹¹ Synthesis of alkenyl products is possible by using 1-alkenyl copper reagents produced by using a corresponding lithium reagent instead of Grignard's reagent through arylation and methylation synthesis. Do.

However, with the above-described prior art, the adsorption of the electrode and the fullerene is not easy, and the adsorption with the gold electrode is still easy, and the organic rectifier having an aligned arrangement between fullerene molecules and the fullerene derivative used therein are still developed. Will do this is requested.

[ (1) Metzger, RM Chem. Rev. 2003 , 103 , 3803. (2) Aviram, A; Ratner, MA Chem. Phys. Lett. 1974 , 29 , 277. (3) Martin, AS; Sambles, JR; Ashwell, GJ Phys. Rev. Lett. 1993 , 70 , 218. (4) Metzger, RM; Chen, B.; Ho¨pfner, U.; Lakshmikantham, MV; Vuillaume, D.; Kawai, T.; Wu, X.; Tachibana, H.; Hughes, TV; Sakurai, H.; Baldwin, JW; Hosch, C.; Cava, MP; Brehmer, L.; Ashwell, GJ J. Am. Chem. Soc. 1997 , 119 , 10455. (5) Metzger, RM; Xu, T.; Peterson, IR J. Phys. Chem. B 2001 , 105 , 7280. (6) Metzger, RM; Baldwin, JW; Shumate, WJ; Peterson, IR; Mani, P.; Mankey, GJ; Morris, T.; Szulczewski, G.; Bosi, S.; Prato, M.; Comito, A.; Rubin, Y. J. Phys. Chem. B 2003 , 107 , 1021. (7) Honciuc, A.; Jaiswal, A.; Gong, A.; Ashworth, K.; Spangler, CW; Peterson, IR; Dalton, LR; Metzger, RM J. Phys. Chem. B 2005, 109, 857. (8) (a) Shi, X.; Caldwell, WB; Chen, K.; Mirkin, CA J. Am. Chem. Soc. 1994 , 116 , 11598. (b) Arias, F.; GodKnez, LA; Wilson, SR; Kaifer, AE; Echegoyen, L. J. Am. Chem. Soc. 1996 , 118 , 6086. (9) Zareie, MH; Ma, H.; Reed, BW; Jen, AK-Y.; Sarikaya, M. Nano Lett. 2003 , 3 , 139. (10) Nakamura, E; Isobe, H. Acc. Chem. Res. 2003 , 36 , 807. (11) (a) Sawamura, M.; Iikura, H.; Nakamura, E. J. Am. Chem. Soc. 1996 , 118 , 12850. (b) Sawamura, M.; Iikura, H.; Ohama, T.; Hackler, UE; Nakamura, E. J. Organo-metal. Chem. 2000 , 599 , 32 . (c) Sawamura, M.; Toganoh, M.; Kuninobu, Y.; Kato, S.; Nakamura, E. Chem. Lett. 2000 , 262. (d) Sawamura, M.; Nagahama, N.; Toganoh, M.; Nakamura, E. J. Organometal. Chem. 2002 , 652 , 31. ]

A first object of the present invention for solving the above problems is to provide an amphiphilic fullerene derivative having a pentapod structure having various functional groups including sulfur by introducing a thiolating method.

Further, a second object of the present invention is to provide an organic rectifier using a fullerene derivative obtained by achieving the first object.

In order to achieve the first object, the present invention provides a fullerene derivative _{having an amphiphilic property of a pentapod structure and having a formula of (RX) 5 HCn.}

In the above formula, the functional group RX is a functional group having sulfur, and n is 60 or more.

The present invention for achieving the second object, a conductive substrate; And fullerene derivatives formed of a Langmuir volt single film or a self-assembled single film on the conductive substrate, wherein the fullerene derivative is a system having an electron donor-insulated δ bridge-electron acceptor part in one molecular structure. It provides an organic rectifier characterized by.

According to the present invention as described above, a fullerene derivative of a pentapod structure containing a thiol or a thiol derivative as a functional group is capable of a perfect monomolecular mono-arrangement due to the strong adsorption of the thiol functional group to Au (111). ) It is easy to control and shows rectification phenomenon at forward low voltage. As a result, these molecular rectifying materials can be applied in a variety of applications in nano-sized devices such as memory materials.

Hereinafter, preferred embodiments according to the present invention will be described in detail with reference to the accompanying drawings.

Embodiment 1

1 shows the structure of a fullerene derivative according to a preferred embodiment of the present invention.

Referring to FIG. 1, a fullerene derivative having a pentapod _{structure of amphiphilic properties and a formula of (RX) 5 HCn is disclosed.} In the above formula, RX is a functional group having sulfur. Specifically, R is a linear or branched saturated or unsaturated alkyl or aryl group, and X includes a structure of -SH or -SS- as a moiety of a functional group that can be adsorbed with the substrate surface. Specific examples of RX are as shown in FIG. 1.

The synthesis of the fullerene pentapod was carried out using a penta-addition method, which is very easy and shows a yield of over 90%. (RX) _{As an example of a fullerene derivative having a formula of 5} HCn, a fullerene derivative having a pentapod structure containing a thiol and a thiol derivative as a functional group, that is, (4-SX'-C ₆ H ₄ ) ₅ HCn Synthesis was successful, where X'may be a protecting group such as pyran. In the formulas of the fullerene derivative, n is preferably 60 or more.

That is, five thiolated (-SX') functional groups are provided in the fullerene molecule. The structure of the functional group bonded to the fullerene molecule is shown in detail in FIG. 1.

In addition, from molecular mechanics (MM2) studies, it was expected that the functional groups of thiols and thiol derivatives that form the bridge of fullerene would act as donors, and that the fullerene portion would act as an acceptor. It was confirmed as in FIG. 6 through computer simulation that both the Highest Occupied Molecular Orbital (HOMO) and the Lowest Unoccupied Molecular Orbital (LUMO) exist in the fullerene cage.

This is contrary to that of previous fullerene rectifiers, in which case the five thiolated (-SX') functional groups not only help to connect with the substrate, but also provide a fixed support for the fullerene molecules. Therefore, the amphiphilic fullerene pentapod itself, in which this HOMO and LUMO are placed in a fullerene cage, can be called a single molecule rectifier.

Preparation Example 1: Preparation of bromo-phenylsulfanyl-tetrahydro-pyran and Grignard reaction using the same

Preparation of bromophenylsulfanyl-tetrahydro-pyran

To a solution in which bromobenzenethiol was dissolved in dichloromethane (MC) with 3,4-dihydro-2H-pyran, a trace amount of camphor sulfonic acid was added as a catalyst as a catalyst, and then reacted at 40° C. for 3 hours.

As the reaction solvent, not only dichloromethane, but also chloroform, tetrachlorocarbon, etc. can be used, and the reaction solvent is preferably used 10 to 20 times the weight of bromobenzenethiol. At this time, the above protection reaction is carried out in the range of 20°C to 60°C, and when the reaction temperature is less than 20°C, the yield is lowered, and when the reaction temperature exceeds 60°C, there is a problem of occurrence of an addition reaction.

Grignard reaction using bromophenylsulfanyl-tetrahydro-pyran

Referring to Scheme 2, since the Grignard reaction is very sensitive to moisture, the reaction vessel is completely dried and refluxed with nitrogen or argon. After sufficiently refluxing, dried magnesium metal (Mg) is added, and a trace amount of anhydrous tetrahydrofuran (THF) is added to the level of magnesium metal, followed by stirring. In a state of stirring and reflux, 1,2-dibromoethane is slowly added to activate magnesium, and at the same time, THF is slowly injected under an ice bath to prevent overheating reaction. After confirming that the color of the reaction solution has turned dark brown, bromophenylsulfanyl-tetrahydro-pyran is slowly injected. Refluxed at 80° C. for 2 hours and the reaction was terminated. Through this, bromomagnesium-phenylsulfanyl-tetrahydro-pyran (BMPST) can be obtained.

Preparation Example 2: Thiolate fullerene pentapod (4-SH-C ₆ H ₄ ) ₅ HC ₆₀ Manufacture of

The preparation of thiolated fullerene pentapod (4-SH-C ₆ H ₄ ) ₅ HC ₆₀ is as described in Scheme 3 above. More specifically, and reacted for a fullerene (C ₆₀₎ and a copper catalyst, and toluene / tetrahydrofuran was dissolved in a mixed solvent, slowly adding the BMPST prepared in Scheme 2 from -78 ℃, and 2 hours. After raising the temperature to room temperature, an ammonium chloride solution is added to perform a termination reaction.

Using such a protection reaction, the addition reaction in which thiol groups (-SH) react with each other is prevented, thereby obtaining _{(4-(SC 5} H ₅ O)-C ₆ H ₄ ) ₅ HC _60. At this time, in the step of adsorbing with Au (111), when the use of thiol group (-SH) is required, the thiol functional group protected by pyran is converted into a thiol (-SH) functional group in-situ to be used. -Inject toluic sulferic acid or tetra-n-butylammonium fluoride under the addition of a solution in which trifluoroacetic acid is dissolved in methanol. From Scheme 3, the final product (4-SH-C ₆ H ₄ ) ₅ HC ₆₀ was prepared in 95% yield.

The structure of the (4-(SC ₅ H ₅ O)-C ₆ H ₄ ) ₅ HC ₆₀ was attached to FIG. 2 ^{with 1} H-NMR as confirmation data.

Embodiment 2

In the case of a conventional organic rectifier, it has a structure in which a fullerene is disposed between an upper electrode and a lower electrode. Therefore, in order to measure the electrical characteristics of the organic rectifier, a method of applying power to the upper electrode and the lower electrode is used.

However, the fullerene derivative prepared by the present invention adsorbs the fullerene derivative only on the lower substrate. In the thiolate fullerene pentapod structure manufactured according to the first embodiment, the electron donor-δ bridge-electron acceptor system is constructed in a mono layer.

Therefore, the measurement of the rectification characteristics of the conventional organic rectifier is performed after arranging organic materials between the upper and lower electrodes, but in the present invention, a new measurement method is used. (111) is used, and a fullerene derivative is arranged on the conductive electrode. In addition, the tip of a conducting AFM (CAFM) measuring device was used as an electrode on the top of the fullerene derivative. In addition, the conductive electrode has conductivity and is made of gold, silver or platinum.

The measurement of rectification characteristics using the above-described measuring device prevents the rectification characteristics due to tunneling between electrodes occurring in the conventional method, so that the correct rectification characteristics of organic materials can be measured, and the accurate rectification characteristics of the monolayer can be measured. We have suggested a way to do it. Hereinafter, it is described that the method of measuring the rectification characteristics of the fullerene derivative was measured using CAFM.

Preparation Example 3: Preparation of an organic rectifier using conductive AFM (Atomic Force Microscopy) 1

[Structural Formula 1]

Pentapod (4-perthiolated) in-situ using tetra-n- butylammonium fluoride (TBAF) dissolved in tetrahydrofuran (THF). SX'-C ₆ H ₄ ) ₅ HC ₆₀ was activated (deprotected).

In the molecular formula of the perthiolated pentapod, X'is a protecting group such as a pyran moiety.

First, (4-SX'-C ₆ H ₄ ) ₅ HC ₆₀ (1.5 mmol) was dissolved in tetrahydrofuran (10 mL), and the Au (111) substrate was immersed in the prepared solution. A solution in which -n-butylammonium fluoride (8 mmol) was dissolved was added to adsorb the fullerene derivative and the substrate for 12 hours, washed repeatedly with tetrahydrofuran, and dried with _{nitrogen gas (N 2 ).} Then, it was dried for 24 hours in a vacuum desiccator under nitrogen dried at room temperature. The IV characteristics of the prepared device were analyzed in the air using a conductive AFM.

I-V characteristics of the device manufactured above are attached to FIGS. 3 and 5.

Preparation Example 4: Preparation 2 of an organic rectifier using conductive AFM (Atomic Force Microscopy)

[Structural Formula 2]

_{Perthiolate pentapod (4-SH-C 6} H ₄ ) ₅ HC ₆₀ prepared by in-situ activation (deprotection) was mixed with mercaptooctanoic acid (MOA) and mercaptododecanoic acid. ; Mercaptocarboxylic acids such as MDA), mercaptohexadecanoic acid (MHA), mercaptosuccinic acid (MSA) or thioctic acid (TOA). ) And formed a hydrogen bond.

To this end, first, a self-assembly monolayer (SAM) of mercapdocarboxylic acid was made on the substrate. For example, a solution of MHA was made by dissolving MHA (1.5 mmol) in THF (25 mL). In addition, a clean Au (111) substrate was immersed in this solution at room temperature for 24 hours, washed several times with THF, and then dried with nitrogen gas. After that, it was dried in a vacuum desiccator for 24 hours. Perthiolate pentapod (4-SH-C ₆ H ₄ ) ₅ HC ₆₀ was adsorbed on the SAM-converted substrate by in-situ activation (deprotection). Its IV properties were measured using conductive AFM in air.

I-V characteristics of the device manufactured above are attached to FIGS. 4 and 5.

Although the above has been described with reference to preferred embodiments of the present invention, those skilled in the art will variously modify and change the present invention within the scope not departing from the spirit and scope of the present invention described in the following claims. You will understand that you can do it.

1 shows the structure of a fullerene derivative prepared according to the present invention.

^{Figure 2 shows the 1} H-NMR spectrum of the thiolate fullerene prepared in Scheme 3 according to the present invention.

3 is an I-V curve of the device manufactured in Preparation Example 3 according to the present invention. Bias voltage: -1 V ~ +1 V.

4 is an I-V curve of the device manufactured in Preparation Example 4 according to the present invention. Bias voltage, (A) -2 V ~ +2 V, (B) -3 V ~ +3 V.

5 is a comparison graph of the I-V curves of the devices manufactured in Preparation Examples 3 and 4 according to the present invention.

6 is (A) HOMO and (B) LUMO results _{of (4-SH-C 6} H ₄ ) ₅ HC ₆₀ through a computer simulation of a fullerene derivative prepared according to the present invention.

Claims (3)

Fullerene derivative of pentapod structure represented by the following formula (1). [Formula 1]

In Formula 1, the functional group RX is a functional group having sulfur. According to claim 1, wherein in the functional group RX R is a linear or branched saturated or unsaturated alkyl or aryl group, X is a structure of the functional group that can be adsorbed to the substrate surface in the structure of -SH or -SS- Fullerene derivatives. The fullerene derivative according to claim 1, wherein RX is at least one selected from the group consisting of the following formulas.

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